Manufacture of fluoro butanes



MANUFACTURE OF FLUORO BUTANES Cyril Woolf, Morristown, N .J., assignorto Aiiied Chemical Corporation, a corporation of New York No Drawing.Filed Dec. 13, 1957, Ser. No. 702,522 6 Claims. (Cl. 260-653.7)

This invention is directed to processes for manufacture of 1,1,1,2,4,4,4heptafiuoro 2,3,3

trichloro butane,

CF CClFCCl CF a clear, colorless liquid having a boiling point of 98 C.at atmospheric pressure. This material is a known compound of commerce,and is useful as a coolant.

It has been proposed to make CF CClFCCl CF by high pressure autoclavereaction of cF,cc1=cc1cF, with hydrogen fluoride and chlorine in thepresence of pentavalent antimony catalyst. With regard to fiuorinatingprocesses in general utilizing the antimony route, operating proceduresare subject to many recognized disadvantages among which arethe'corrosiveness of the antimony halide, the. difiiculty of operationinvolved by reason of the use of liquid reactant as distinguished from asolid catalyst, and the relatively high volatility of antimony halidesthereby giving rise to formation of products which contain small amountsof'the fluorinating agent as impurity which is not easily removed. Whilepracticable, the disadvantages of the fluorination operations involvinguse of antimony salts are apparent to, those skilled in the art.

A major object of the vision of a solid catalyst, gas-phase method formaking CF CClFCCl CF by HF fluorination of certain butane or butenestarting materials while in the presence or absence of elementalchlorine.

In accordance with the invention, it has been found that a certain-classor group of butanes or butenes or mixtures of both possess physical andchemical properties such as to render these compounds particularlysuitable organic starting materials for production of cF,co1Fcc1,cF, bycatalytic gas-phase operation. Further-, it has been found that certainzirconium-activated carbon materials possess the properties ofeffectively promoting reaction, in the presence or absence of elementalchlorine, of

aqueous solution of a zirconium salt, such present invention lies in theproadding the liquid to grams of the 2,981,762 Patented Apr. 25, 1961ice a colorless liquid, B.P. of about 104 C.;

CF CHClCHClCF a colorless liquid, B.P. of about 78 C.;

CF CH CHCICF a colorless liquid, B.P. of about 51 C.;

CF CH CH CF a colorless liquid, B.P. of about 24.6" C. and butenes suchas CF CCl:CClCF a colorless liquid, B.P. of about 67 C CF CH:CC1CF acolorless liquid, B.P. of about 35 C.; CF CH:CHCF a colorless liquid,B.P. of about 33.2" C.; and CF CH:CHCF trans isomer, a colorless liquid,B.P. about 85 C. All the foregoing compounds are characterized by beingfluorinated straight-chain 4 carbon atom hydrocarbons both primary orterminal carbon atoms of which are fully substituted by fluorine, andboth secondary carbon atoms may containa total of from zero to 4chlorine atoms, and are free. of other substituents, that is, secondarycarbon atoms are linked to only chlorine or hydrogen or to chlorine andhydrogen.

The catalytic material utilized in practice of the invention may be madefor example by impregnating activated carbon, of say 4-15 mesh sizegranulation, with an as zirconyl chloride ZrOcl and drying at -200 C. inan inert gas stream such as nitrogen. Then the material is gassed withHP to convert the zirconium to ZrF temperatures being maintained above125 C. and preferably at about ISO-200 C. Water and HCl formed duringthe reaction pass off in the vapor state. Gassing with HF is continueduntil tail gases of the HF gassing operation indicate that evolution ofHCl and water has ceased.

Raw material serving as the source of zirconium may be any zirconiumsalt whichis soluble in vaporizable solvent and which reacts with HF toform ZrF and a by-product vaporizing at the temperature of HF gassing.Thus, materials such as ZrOCl ZrO(NO and ZrOCO .ZrO(OH) and alsoanhydrous ZrCl, may be used. While aqueous hydrochloric acid and waterare the more desirable solvents, other suitable solvents may beemployed. For example, a catalyst containing 20 weight parts of ZrF per100 parts of Columbia 66 carbon may be made by dissolving 28 grams ofsubstantially anhydrousZrCl, in 200. cc. of 10% hydrochloric acid,carbon, evaporating to dryness, transferring the impregnated carbon intoa tubular nickel reactor heated by electric furnace, and passingpreferably anhydrous HF into the impregnated carbon maintained at about-200 C. until evolution anhydrous HF and the herein organic startingmaterials.

Hence, the invention comprises the discovery or selection of certainstarting materials, and the conjunctive relation of the same with theherein zirconium salt. catalysts and certainreaction conditions, whichinterrelated factorsresult in provision of an easily controllable, allgas-phase truly catalytic procedure, in accordance withwhich the desiredCF CClFCCl CF may be made in good yields. i

The butane and butene starting materials of the inventionprocess, arefluorinated straight-chain 4 carbon atom hydrocarbons both primarycarbon atoms of which are trifluorinated and both secondarycarbon atomsof which 3 contain a total of zero to 4 chlorine atoms and are free ingmaterials include: butanes such as CF CCI CCI CF, I p

colored solid having a melting p ointi of other substituents. Specificexamples of these start- 4 normally a white of. 835C. and of about 131C.,

of water and HCl ceases. i

In making the catalyst, any of the commercially available activatedcarbons may be employed, e.g. Columbia 66 carbon, Columbia SW carbon, orDarco carbon. -The relative, quantities of activated carbon andeg.Zirconyl chloride initially employed may be such as to form ,an

ultimate zirconium tetrafluoride-activated carbon mass which containsdesirably a major quantity by weight of activated carbon anda minorquantity by weight of ZrFg. On the other hand, amounts of zirconium saltand activated carbon may be such. as .to form a final zirconiumtetrafluoride-activated carbon catalyst contain- 'ing as little as about5% by weight of ZrF The catalyst preferably employed in practice of theinvention may be considered .as a zirconiumtetrafiuoride on activatedcarbon mass containing about 540% by weight of ZrF --.Practice of theinvention involves subjecting gasphase starting material--such startingmaterial being a fluoriated straight-chain 4' carbon atom hydrocarbonboth primary Icarbon atoms} of which are trifluorinated'. and, p t nboth secondary; carbonatoms'of which-contains. total of,

The more desirable starting materials, whether saturated or unsaturated,are those containing no hydrogen. The preferred individual startingmaterial is the saturated perhalogenated compound CF CCl CCl CF .In allembodiments of the invention, reaction temperature should be not lessthan about 275 C. However, at about 300 C. in the presence of HF and thedescribed catalyst, and in the presence of elemental chlorine itrequired, more practical fluorination takes hold, and progresses atreasonable contact time. It has been found that at temperatures aboveabout 390 C. fragmentation, with formation of some ethane by-product, isincipient. Accordingly, temperatures above about 390 C. are undesirablein some circumstances, and it has been found that bestyoverall resultsare obtainable in the preferred temperaturerange of 300-350 C. Ifoperating conditions are such that some fragmentation is not practicallyobjectionable, temperatures may be as high as about saturation and/ orfull substitution by chlorine of the secondary carbon atoms may beeffected in a separate preliminary stage, e.g. by subjecting suchstarting material to the action of adequate quantities of chlorine aloneat temperatures ofsay 250- to 350 C. in the presence of suitablecatalystssuch as activated carbon. However, an advantage of theinvention, arising out of the use of the describedzirconium;tetrafiuoride-activated carbon cat- -alyst,"is that saturationif necessary, and full substitution by chlorine of secondary carbonatomsif necessary, together with fluorination may be effected convenientlyina single reaction stage.

.Where the starting material employed-is other than CF CCl CCl CF ih thepreferred embodiments, fluorination is carried out while in the presenceof sufficient chlotime to provide for any unsaturation of the startingmateri-als and for any incomplete chlorination of secondary carbon'atomsof such starting material; Theoretical requirementsas to quantitiesof;chlorine.needed in various modifications ofthe invention areindicated above. In-

large-scale work, whenfchlorine is employedfit is pre ferred to utilizeelemental chlorine in amount equivalnt to a relatively small, e.g. 3-7weight percent molecular excess over that needed theoretically toprovide for any unsaturation and for any incomplete chlorination ofsecondary carbon atoms.

Mol ratio of HF to organic starting material is variable to some extent.Theoretical requirements of HF are one mol of HF per mol of butane orbutene. In any case, enough anhydrous HP is employed to react with asubstantial amount of the particular starting material to form asubstantial quantity of CF CClFCCl CF While more than theoreticalquantities of HF may be employed, it is desirable to use quantities ofHF which approach but do not substantially exceed stoichiometricproportions. It has been found that, when employing the catalystsdescribed, if the HF molar ratio is increased appreciably above the 1:1ratio, utilization of HF decreases markedly with insufficient worthwhileincrease of product formation. In large-scale work, to effect higherutilization of HF, it is preferred to employ HP in amount equivalent toa relatively small, e.g. 1020 weight percent molecular deficiency basedon theoretical requirements.

Contact time may be varied considerably without noticeable disadvantageto high process efliciency. Increasing contact time and reactortemperature result in higher HF conversion and higher conversion ofstarting material to soughtfor product, and lowering contact time andreactor temperature result in lower HF conversion. In

general, contact time may lie in the range of 2 to 30 sec ends, andpreferably in the range of 5-15 seconds. To a substantial extent,contact time, reaction temperature and ratio of reactants areinterrelated, and product formation may be varied by alteration of oneor more of these factors. Depending upon the starting material used,optimum conditions may be determined by test runs.

In general practice, organic starting material and anhydrous HF arevaporized and metered, along with chlorine if needed, into a tubularreactor packed with catalyst, and made of suitable inert material suchas nickel, and provided with external heating equipment preferablyincluding automatic means for maintaining given temperatures in thereaction zone. Product recovery may be effected more or lessconventionally as in this .art'. For example, reactor exit gases may bepassed into an ice cooled water scrubber to absorb .HCl and anyunreacted or excess HF, and to condense the organic prodnets and anyunreacted starting material. Tail 'gas of the water scrubber may bepassed thru a caustic scrubber to remove any chlorine. Organics andwater may be separated by'stratification and decantation, and afterdrying and filtering, the organics may be separated and isolated bydistillation. V

The following examples typify practice of the invention. A ZrF-on-activated carbon catalyst was made substantially as follows:Commercial ZrCL; was dissolved in water and poured over Columbia 6Gactivated carbon of 4-l4 mesh, the amount of ZrCl eing such that theWeight ratio of carbon to ZrCl was 10:1; The mixture was evaporated anddried at about C., and about 200 cc. were charged into and filled aboutthe middle 16 inches of a reactor comprising a one inch 1D. nickel tubeabout 36 inches long and heated over a length of about 30 inches'by atubular electric heating unit. Temperature was maintained in the reactorat about 200 C: to drive off residual water, aud;then the masswas gassedwith anhydrous HP at about 200 C, until evolution of HCl ceased. Thefinished catalyst contained about 6.7% by weight of ZrF. and about 93.3%by Weight of carbon. The reactor was provided at one end with feedinlets and at the other end with a pipeconnection leading to a recoveryunit.

.ingat 83 Crandboiling at about"l3l C. In view'of the melting point ofCF CCl CCl CF to facilitate metering, there was first made up a solutionof in liquid CF CCl:CClCF (B.P. 67 C.), quantities of organic materialsbeing such that the solution contained 50% by weight of CF CCl CCl CFUnder the conditions of reaction, i.e. the absence of chlorine, the

CF CCl: CClOF functioned only as a diluent and did not react. Duringabout 2 hours, about 0.85 mol of gaseous anhydrous HF, and a vaporousmixture of about 2.20 mols of CF CCl:CClCF and 1.69 mols of CF CCl CClCF were metered and fed into the reactor at approximately constant rate.M01 ratio of CF CCl CCl CF to HF was about 1:0.5. Throughout the run,internal temperature in the reactor was maintained at about 335 C., andcontact time was about 6 seconds. Exit gases of the reactor were passedinto an ice cooled water scrubber in which HCl and any HF were absorbed,and CF CCl:CClCF unreacted CF CCl CCl CF and organic reaction productswere condensed. The oily organic and water layers were separated, andthe organic layer was dried with CaCl and filtered. About 3.9 mols oforganic compounds were recovered. HF utilization was about 76%. Thedried and filtered organic products were distilled, and there wererecovered as condensate about 0.51 mol of an oily colorless liquididentified as CF CClFCCl CF (B.P. 98 C.). Conversion of CF CCl CCl CF-to organic products was about 34% by weight, and yield of CF CClFCCl CFbased on the amount of converted was about 89% by weight.

Example 2.The organic starting material was mols of gaseous anhydrousHF, about 3.1 mols of and about 2.74 mols of elemental chlorine werecharged into the reactor at about constant rate. Mol ratio of organicstarting material to HF was about 1:057, and mol ratio of organicstarting material to elemental chlorine was about 1:0.88. Internaltemperature in the reactor was maintained at about 300-310 C. Off-gas ofthe reactor was handled substantially as in Example 1. About 3.06 molsof organic compounds were recovered. HF utilization was about 46%, andchlorine utilization about 90%. On distillation of the organic compoundsobtained from the reactor, there were recovered as condensate about0.53mol of CF CCIFCCI CF Conversion of organic starting material to organicproducts was about 79% by weight, and yield of CF CClFCCl CF based onthe amount of starting material converted, was about 22% by weight, theremainder of the starting material being substantially all converted towhich may be recycled.

Example 3.Organic starting material employed was CF CH:CClCF (B.P. 35C.), and the apparatus and catalyst were the same as in Example 1.During about 95 minutes 1.7 mols of anhydrous HF, 3.67 mols of elementalchlorine and about 1.57 mols of CF CH:CClCF were passed into the reactorat approximately constant rate. M01 ratio of organic starting materialto HF was about 1:1.08, and mol ratio of organic starting material toelemental chlorine was about 122.2. Throughout the run, internaltemperature in the reactor was maintained at about 425 C., and contacttime was about 2 seconds. Exit gases of the reactor Were handled as inExample 1. HF utilization was about 46%, and chlorine utilization wasabout 100%. The dried and filtered organic products recovered from thereactor were distilled, and there were recovered, a small amount of CFCCl and from about 88 grams of a fraction boiling in the range of 90 C.,about 0.31 mol of CF CClFCCl CF Conversion of organic starting materialto organic products was about 100% by weight, and yield of CF CClFCCl CFbased on the amount of starting material converted, was about 20% byweight.

I claim:

1. The process for making CF CClFCCl CF which comprises subjectinggas-phase starting material--said starting material being a fluorinatedstraight-chain 4 carbon atom hydrocarbon both primary carbon atoms ofwhich are trifluorinated and both secondary carbon atoms of whichcontain atotal of zero to 4 chlorine atoms and are free of othersubstituen-ts at temperatures substantially in the range of 275-425 C.and while in the pres ence of a zirconium tetrafluoride-activated carboncatalyst and while in the presence of sufiicient chlorine to provide forany unsaturation of said starting material and for any incompletechlorination of the secondary carbon atoms of said starting material, tothe action of gaseous anhydrous hydrogen fluoride in quantity and for atime sufiicient to fluorinate a substantial amount of said startingmaterial and to form substantial amount of CF CClFCCl CF and recoveringCF CClFCCl CF from the resulting reaction products.

2. The process of claim 1 in which temperature is substantially in therange of 300-390 C.

3. The process of claim 1 in which material is substantially free ofhydrogen.

4. The process of claim 1 in which, with reference to the organicstarting material, any Chlorine present is present in amountconstituting a relatively small molecular excess over that needed toprovide for any unsaturation and for any incomplete chlorination ofsecondary carbon atoms, and hydrogen fluoride is present in amountconstituting a relatively small molecular deficiency.

5. The process for making CF CClFCCl CF which comprises subjectinggas-phase CF CCl CCl CF starting material, at temperatures substantiallyin the range of 300-390 C. and while in the presence of zirconiumtetrafluoride-activated carbon catalyst, to the action of gaseousanhydrous hydrogen fluoride in quantity and for a time sufficient tofluorinate a substantial amount of said starting material and to formsubstantial amount of CF CClFCCl CF and recovering CF CC1FCCl CF fromthe resulting reac- =tion products.

6. The process of claim 5 in which temperature is substantially in therange of 300-35 0 C., and the operation is carried out, with referenceto said in the presence of hydrogen fluoride in amount constituting arelatively small molecular deficiency.

the said starting References Cited in the file of this patent UNITEDSTATES PATENTS

1. THE PROCESS FOR MAKING CF3CCLFCCL2CF3 WHICH COMPRISES SUBJECTINGGAS-PHASE STARTING MATERIAL-SAID STARTING MATERIAL BEING A FLUORINATEDSTRAIGHT-CHAIN 4 CARBON ATOM HYDROCARBON BOTH PRIMARY CARBON ATOMS OFWHICH ARE TRIFLUORINATED AND BOTH SECONDARY CARBON ATOMS OF WHICHCONTAIN A TOTAL OF ZERO TO 4 CHLORINE ATOMS AND ARE FREE OF OTHERSUBSTITUENTS-AT TEMPERATURES SUBSTANTIALLY IN THE RANGE OF 275-425*C.AND WHILE IN THE PRESENCE OF A ZIRCONIUM TETRAFLUORIDE-ACTIVATED CARBONCATALYST AND WHILE IN THE PRESENCE OF SUFFICIENT CHLORINE TO PROVIDE FORANY UNSATURATION OF SAID STARTING MATERIAL AND FOR ANY INCOMPLETECHLORINATION OF THE SECONDARY CARBON ATOMS OF SAID STARTING MATERIAL, TOTHE ACTION OF GASEOUS ANHYDROUS HYDROGEN FLUORIDE IN QUANTITY AND FOR ATIME SUFFICIENT TO FLUORINATE A SUBSTANTIAL AMOUNT OF SAID STARTINGMATERIAL AND TO FORM SUBSTANTIAL AMOUNT OF CF3CCLFCCL2CF3, ANDRECOVERING CF3CCLFCCL2CF3 FROM THE RESULTING REACTION PRODUCTS.